Not really bidding, it is a way to sell geocoins, you choose a coin and make an offer on that coin, if the seller likes your offer than you purchase the coin. Sold as is usually means that they have been sitting around a while and may be tarnished or scratched, usually the seller will let you know if they have been activated and are then adoptable. New Batch of 50 means that he just list 50 new different coins for sale. Hope that clears up any confusion.